No disclosure of a halogen substituted pyrazino-oxazine has been found in the literature. Hexahydro-2'-methylspiro(cyclohexane-1,8'(6H)-oxazino(3,4-A)pyrazine) is included in a list of compounds reported by G. Chen, Proc. Soc. Expt. Biol. Chem., 112, 611 (1963) to have been examined for convulsant properties, this is the closest known prior art compound to the pyrazino-oxazines of the present invention.